Automatic telephone-exchange system.



, I. WUHLER. AUTOMATIG TELEPHONE EXOHANGE SYSTEM.-

' urmm'non FILED nmso, 1912.

Patented Mar. 4, 1913.

- y =1 EH11? W/IHesses: v I

' exchange lines, stations TelephoneEXchange Unreal) STATES PATENT orrion FRIEDBICH WHLER, OF HANOVER-LINDEN, GERMANY, ASSIGNOR '10 WESTERN ELEC- THIS COMPANY, OF NEW YORK, N. Y.

" GQBPQRATION OF ILLINOIS.

AUTOMATIC TELEPHONE-EXCHANGE SYSTEM.

To all whom it may concern: I

Be it known that I, FRIEDRICH Winnie,

the German Empire, and a resithe Kingdom of Prussia, Germany, have invented certain new and useful Improvements in Automatic Systems, of which the following is a specification.

This invention relates to telephone exchange systems in which existing. talking connections are automatically disconnected in favor of more important connections. Thecircuit arrangements previously known for automatically operated central oflices for groups of subscribers entitled to diil'erent classesor grades of service, as for instance, hav ng the privilege of using exchange lines, and private or unprivileged stationsthat are not allowed to use any but exchange lines, either required special lines to be provided for the trafiic between the various subscribers in such a manner that one and conversing .with various groups of subscribers was obliged to make use of various lines, or else more than the one customary. test wire for indicating the busy condition or for immediately severing an existing connection was necessary.

The invention relates to a cprcuit arrangement in which the one customary tests-wire is possible also seem to be of more sufiices for indicating the I the line in question as well as for the forcible disconnectibn of the existing connection and the simultaneous connection of a new one.

The fact that the various groups are en- ,titled to various classes of the prescriptions of various postal adminisservice is due to 'trations, that a privileged station may conline as well-as with unprivileged stations whereas no connection between exchangev lines and un- A conversation on an privileged stations.

always be of exchange line would probably greater importance than a conversation be-, tween two privileged stations, two unprivileged stations,

or between a privileged station and an unprivileged one. A conversation between two privileged stations would importance than one between a privileged station and anunprivileged station in case the connection was made by the latter.

In order to make possible the establish- Specification of Letters Patent.

the same subscriber in busy condition of Patented Mar. 4.. 191 3.

Application filed December 30, 1912. Serial No. 735,244.

ment of a new connection by terminating the existing connection, according to the class of conversation, on. by hindering the establishment of a connection of less importance,- it is only necessary according to the invention "to provide the release magnets of theselecto-rs of the individual groups of subscribers with two windings, the first of which is connected to the test wire during the busy test of a line, usually in position Q-of the control switch, while the second is connected to the test wire after the completion of the connection, that is, 'in position 3 of the control switch. If the release magnets are-provided with two windings, of which one is connected to the test brush of the corresponding selector during thetestiiig operation, and the other during the convrsation, the first one becoming efiective at a lower current strength than the last one, and if this relative grading of the sensitive ness of the release magnets of the talking stations pertaining to the various classes of groups is so carried out that of the windings of the release magnets that are connected in series through the addition of another talking station during the testing of an existing connection, that of the station of lesser importance is always the more sensitive one, and finally if the test potential also is graded corresponding to the importance ofthe testing stations, so that the potential set up in the release magnet windings connected in series by a third station in testing an existing connection can only cause the winding of the station of lesser importance to respond, an existing connection between two stations can only be severed by a station belonging to a more important class than the station which effected the previously existent connection.

In the attached drawings: Figure 1 is a diagrammatic view of the system and Fig. 2 is a view of a special form of relay which is used in connection therewith.

P 1 indicate p'ublic connection selectors, N N? the privileged selectors and H, H unprivileged selectors.

S is the switch shaft with the switch contact s and the control switch U which may take the three positions 1, 2 and 3. The test wires, which so to 'say emanate at the cor- 1responding selector, are of course connected in the same manner as the talking wires (not shown) to the fixed selector contacts of those privileged station N selectors with lowed. The busyvtestof a line isfidcted in position v 2 Yet. the control switch control switchiremainingin positionB uring the duration of the-talking connect on. The release magnets of the various selectors are indicated by the two windings a and b of the un rivileged selectors, c and d of the privileged selectors, and e and f off the public connection Selectors, which, for instance, are intended to respond in the same order to l, 3, 5, 7, 9 and ll'amperes, being so'connected to the poles of a divided battery that'there is a potential between the two windings of one and the same release magnet causing the, first winding only (position .2 of the switch) to respond when both windings are connected in series.

Let it be assumed that the unprivileged 2o station H has obtained connection to the unprivileged'station H The brush 8 of H is therefore located on the fixed selector contact H and switch U is in position 3. The

tain connection to H by connecting over the test wire,

in position 2 of its test switch U, the winding 0 of its release magnet to the winding 2) of the releasemagnet H I over the following path: terminal K lines 20, 21, winding 6 of magnet H lines 22, 23-, brush 8 of N switch U, winding 0, lines 24, 25 and back to terminal K of battery Ba. The windings are connected to four electrical potential units of the current source Ba, their resistance being so measured 'that acurrent of, for instance, 4 amperes' flows which solely causes the release magnet of H which already responds at 3 amperes, to take effect and interrupt the existing connection, whereas thenew connection of'N with H is closed owing to the winding 0 of N 2 not receiving suflicient current to enable it to respond. The same would have been the case 11 N were to attempt to occupy the un rivileged station H ,-the connection of 1 with H would have been released in the same manner. f the. privileged station N has called up the public connection line P, neither another privileged station nor an unprivileged station can release the connection owin to the fact that the. winding d of station N as a further privileged station-N on testing, would connect the winding 0 which already responds at 5 a-mperes.

the privileged c and d being-connected in series, produce a current of 5 amperes.

f an unprivileged station should wish to obtain connection to a which talking trafiic is Three the ' and solely making now attempts to ob-- relay. remaining only responds at 7 amperes where. since their resistance e 6 potential: units are connected at the battery, which; on -net of N only would;

ture and cause therelease of the associated. I

parts are essential for a I roper mode of operation, namely, the first winding of the one release magnet, the second windmg the -other release magnet, and a certam partof the-battery,-these three parts being connected in series on each occasion. If the two windings comingin question'are of diiferent, properly graduated, resistance, only therelay of higher resistance will respond on each occasion, the relay of lesser resistance remaining-in normal condition.

The problem ;may be manner than by the aforementioned one, namely, by making all the necessary relays, or release magnets, of all the groups, of the same construction and of equal resistance the armatures of the individual electromagnets subject to different counteracting forces (for instance by differently tensioned springs for retaining the armatures in normal position) in such a solved in another manner that of two relays thatare connec'ted III'SGI'IES only the one that responds more easily attracts its armature, that is, that one of which the spring was so adjusted as to cause the armatu tial in question, hereas the armature of the in normal-condition was adjusted in such a manner as to enable it to respond at "a higher potential only. According to this each of the two windings of one and thesame release magnet would have to be provided with an individual armature, of which each one alone would be capable of effecting the restoring of the selector. Such a device is illustrated in Fig. 2 in which the comp is magnetically united piece which supports the two armatures i and j, the movement of armature 7' being retarded-by spring Z. .The windings e, c and a of Fig.1 would surround the left-hand portion of the core 9 while the windings f, d and'b would surround the right-hand portion of the core g. The armatures i and 9' may be arranged to operate relay contacts or to directly bring about the release of the associated cause if the party at station N is talking and the party at N tries to connect with N if one armature were used the windings c of N and (l of N .would be energized and is the same they would pull up their armatures and both would release, whereas if a heavier armature were provided for (1 than for-c, the release magselector.

1 claim combination with a lines each terminating in an automatic switch, a test circuit for each of said switches including a arrangement pull up its armasingle test brush, means with the heel I switch. This is necessary ben5 1.. In a telephone exchange system, the

plurality of groups, of

- ed to selectively .istic electrical condition.

istic of the group of lines for placing on saidtest circuit an electrical condition characteristic of the group of lines to one of which the switch is connect- .ed, and an electro-responsive device of a busy line includedin said test circuit adaptrespond to said charactersuch potential and not to another. telephone exchange system, the- 3. In a combination with a plurality of groups of lines each terminating in' an automatic switch, a' test circuit for each of said switches includingv a single test brush,

means for impressin a potential characteristic of the group 0 lines to. one of whiqh;

the switch is connected, and a release magthe release magnet net for each of said switches, said test circuit including also said release magnets, whereby, upon the release magnet of a testing switch being included in circuit with the-other of said release magnets will be energized according to the potential 1mbrush of the testing.

pressed upon the test switch. V

4. In a telephone exchange system, the combination with a plurality of groups of connection has been of a busy switch one or 1 lines each terminating in an automatic switch, a test circuit switches including a single test brush means for impressing a' potential characteristic of the group of the switch is connected and a release magnet for each of said switches, the resistanceof the magnets being graded in groups corsaid test responding to the line grouping,

magnets,

circuit including also sald release for each of said lines to one of which whereby upon the release magnet of ates'ting'switchbeing included in ,circuit with the release magnet of a busy switch, one or fthe other of said release magnets will be energized according to the relative IBSISF ances of the magnets and the potential impressed upon the test brush-1 of the testing switch.

combination with a plurality of lines, automatic switches for interconnecting the-same having a testcontact for each line and a testebrush adapted to contact therewith, re- .lease magnets for said switches having two Ina telephone exchangesystem, -the coils, one connected to said test brush when r the switch is testing and the other after the established the first winding, being eflective toenergize the magnet at a lower current strengththan theother. I v e In witness whereof, I hereunto subscribe myv name this twenty ninth day of November A. D. 1912.

' FRIEDRICH VVOHLER. Witnesses .7 I GUSTAV Bnssn,

.Monmsn RoPLqN.

Copies of this patent may be obtained for five cents each, by' addres ing th commissioner f patents,

- 1 Washington, 50. c." 7 A 

